The median transaction fee for XMR is currently around $0.0010, while the median transaction fee for BTC is currently around $5.0973. This means that it would cost 5,097 times more to send a transaction with BTC than it would with XMR.

The question then becomes if Monero's value goes up, does this ruin the fungibility of Monero / XMR?

To answer:

The block size of the Monero blockchain is adjusted dynamically based on the network's hashrate. This ensures that the block time remains relatively constant, even if the price of XMR fluctuates wildly. Does this make mining fees (especially in 30-60 minute intervals) possibly an issue if the fluctuations are absolutely ridiculous?

This is obviously an impossible question that the "why" or "how" XMR (or basically any "valuable" cryptocurrency for that matter) is determined, and what impact that has on transaction fee rates. For now, at XMR's current valuation transaction fees aren't that bad; however, if XMR hit 100k overnight, obviously we have an issue. Does anyone have an opinion on this, or is it exactly how it sounds? That is, perhaps, a disaster if the cost 1 XMR makes .00001 XMR seem like "too much" to pay a miner for the fee?

Loving you all.